The clinical diagnosis of HAE-C1-INH is usually based on the appearance of typical clinical manifestations of the disease, such as non-inflammatory subcutaneous angioedema lasting more than 12 h, abdominal pain of undefined organic etiology lasting more than 6 h, swellings not associated with wheals and which do not improve with anti-histaminergic drugs, and recurrent laryngeal edema (3). The gene discussed is SERPING1; the disease is hereditary angioedema.